With the increased capacity of batteries, electrical apparatus using batteries is often, as with electrical apparatus using ordinary commercial power sources, provided with overcurrent protection devices such as thermistors and the like, which cut off the current flow when there is current exceeding a certain level. As mobile products such as digital cameras and video cameras become more popular, the market ratio of such electrical apparatus provided with overcurrent protection devices is also increasing.
In the above electrical apparatus in the prior art, the overcurrent protection device is provided in the main circuit substrate comprising the electrical equipment. Thus, if a short circuit occurs through some failure in a position closer to the battery than the circuit substrate, the overcurrent protection device will not function, and in some cases the batteries may overheat rapidly and fail.
This invention was made in view of the above circumstances and has the purpose of preventing the battery from failing even if a short circuit occurs through some failure in a position closer to the battery than the circuit substrate and ensuring the integrity and safety of electrical apparatus.